Multiple Services

Defining Multiple Services

• Docker compose shine when you want to run multi-container app.
• Even if you want to run multiple container, you can run your app using single command.
• Let's add mysql service in our compose file.

We will define mysql service but our app won't try to interact with database at the moment.

services:
  myApp:
    image: amantuladhar/docker-kubernetes:v1-web
    ports:
      - 9090:8080
  myDb:                                    #  1
    image: mysql:5.7                       #  2
    environment:                           #  3
      - MYSQL_ROOT_PASSWORD=password       #  4
      - MYSQL_DATABASE=docker_kubernetes   #  4

• #1 name of new service.
• #2 image you want to run. You can use build if you want to.
• #3 Passing environment variables to image. Like we did with -e option.
• #4 List of environment variables
• One new thing in this service is that we are setting environment variables in the file.
• Remember when you had to do this in command, those are old days now :).

Listing the running services

• If you want to list the running services you can use docker-compose ps

Attach mysql terminal

• docker-compose exec @servicename @cmd
• If you want to attach mysql pseudo tty to host, we can do that too.
• docker-compose exec by default attaches the pseudo tty so we don't need to add -it option.
• If you don't want to attach pseudo-tty you can use -T option.
• For now let's use docker-compose exec myDb sh
• Play around with the service, but remember data won't be persisted in next run